1. Field of the Invention
The present invention generally relates to a printing plate lock-up to facilitate clamping a printing plate to and from a plate cylinder in a rotary press without requiring the use of any tools.
2. Description of the Related Art
In a rotary press, a light printing plate is mounted around the circumferential surface of a plate cylinder and fixed thereon in such a manner that the front and rear folded ends of the printing plate are engaged within a recessed groove formed in the circumferential surface of the plate cylinder. The groove is parallel to the plate cylinder axis, and the printing plate is fastened by a fastening means which is manually driven by a special tool.
A typical conventional device is disclosed in Japanese Patent Publication No. 52-22562, entitled "Light Printing Plate Fixing Device on A Plate Cylinder in Rotary Press", hereinafter referred to as Prior Art 1, and is well known.
In the prior art 1, a recessed groove is formed in the circumferential surface of a plate cylinder in a parallel relationship to its axis. On the other hand, a forward folded end of a printing plate is engaged with one edge of the recessed groove and the printing plate is brought into contact with the plate cylinder so as to cover the circumferential surface of the plate cylinder. The recessed groove further includes a rotatable member urged in a predetermined direction. The rotatable member is forcibly rotated against the urged direction by manual operation using a specially designed tool. Then a rear folded end of the printing plate is inserted in a slit formed in the rotatable member. As the rotatable member is released from its rotated position, the rotatable member is turned by the urging force so that the rear folded end of the printing plate is also subjected to the urged force. Thus, the printing plate is fixed on the plate cylinder.
However, the above described conventional device has various disadvantages, such as for example, manual operation of inserting the specially designed tool into the rotatable member of the plate cylinder. This specially designed tool must always be set near the plate cylinder. Further, an operator may have trouble inserting the specially designed tool and returning it to a waiting position.